Computer malware (a shorthand term referring to “malicious software”), generally refers to computer software which enters a computer, typically without the knowledge or intention of a computer user, and when executed by the computer's central processing unit (CPU), causes damage to or disables, or otherwise compromises or interferes with the normal operation of that computer and/or the computer files and systems associated with it. Computer attacks by malware present an on-going and growing risk to computer systems and computer users. For example, in 2013, malware known as “CryptoLocker”, a type of malware known as ransomware, suddenly and rapidly spread across a range of international and domestic networks, and effectively destroyed the files in memory disks/drives of a large number of infiltrated computers by encrypting those files so they could not be opened without co-operation from the malware perpetrator who then sent a ransom message to the computer user demanding payment for the decryption key for the now inaccessible computer files. Other types of attacks include malware theft of confidential information in respect of which the objective of the perpetrator may be to gain valuable intellectual property or publish such private information to cause great embarrassment to the victim.
Therefore, it is desirable to design computers, and computer systems, in such a manner that they can avoid such damage or compromise if and when attacked by malware.